Grigor was very shaky earlier this summer and lost to many guys he shouldn't. Marcel is a good player and if Grigor doesn't put his A game he may very well lose this match. However I think if Grigor shows the shape he has been the last couple of weeks, I don't really see how Marcel will take him out, let alone easily.
It will all depend on how both will serve.
He should be able to get by Ilhan (never seen him play however..) - having said that, crazier things have happened. Overall I'm happy he doesn't have to face either Murray or Nadal until the late stages. (Murray looked 'scary good in his dismantling of Rafa in Tokyo!). Roddick would be tough in the second round - we'll see! He's got a great opportunity here. I watched back the last two tournaments he played (highlights on Youtube) and really liked his serve, forehand, and the depth on his backhand is improving. He seems to get more and more comfortable and holding his own on baseline rallies. His learning curve is picking up and I expect some great results coming up here by the Australian Open next year. I think we're in for some good times)
It was good to see he didn't panic after the 1st set and turned it around big time in the 2nd. Even when he lost the first break at the start of the 3rd, he re-focused and broke back again which is the perfect way to handle these situations. I think he can beat Roddick but he has to start better than today as Roddick is too experienced to let him back in the match.